The present invention relates to an apparatus for quickly determining the percentage of red cells in a blood sample which has been sedimented in a capillary tube. Sedimentation of red cells is usually accomplished by drawing a sample of whole blood into a capillary tube, sealing the tube at one end and subjecting it centrifugal force directed towards the closed end. The red cells, being heavier than the plasma, form a pack at the closed end of the tube with a visible interface between the cells and the clear liquid. The percentage of red cell content is determined by dividing the length of red cell pack by the overall length of the sample and multiplying the quotient by 100. The overall length varies so that two separate length measurements are required.
It is an object of the present invention to simplify these measurements and thus facilitate the determination of red cell content. It is another object of the invention to permit a non-skilled person to make red cell determinations with a minimum of training. It is a further object of the invention to provide a simpler and relatively inexpensive device, compared for example, to the logarithmic scale unit presently used and a more accurate method than the divergent graphs heretofore employed.